Is being gay a sin (or not a sin) in the New Testament - Romans 1:26-27?

Rom. 1:26-27 KJV states, "For this cause God gave them up unto vile affections: for even their women did change the natural use into that which is against nature: (a)nd likewise also the men, leaving the natural use of the woman, burned in their lust one toward another; men with men working that which is unseemly, and receiving in themselves that recompence of their error which was meet."

Rom. 1:26-27 ESV states, "For this reason God gave them up to dishonorable passions. For their women exchanged natural relations for those that are contrary to nature; and the men likewise gave up natural relations with women and were consumed with passion for one another, men committing shameless acts with men and receiving in themselves the due penalty for their error."

Some Christians quote the above passages to justify their belief that being a homosexual is a sin. On first glance, the passages seem to justify their beliefs. However, the two verses are surrounded by other passages which are necessary to explain them. For example: Who is "them" referred to within the first verse? According to Rom. 1:21"For although they knew God, they did not honor him as God or give thanks to him, but they became futile in their thinking, and their foolish hearts were darkened" Rom. 1:21 ESV., Paul is referring to people who were introduced to Jesus Christ and God and then who either became Christians and later denounced their faith or who decided to ignore the teachings of Jesus Christ and God and follow their own pagan beliefs. Moreover, Rom. 1:26 ESV starts with, "For this reason God gave them up to dishonorable passions." For what "reason?" It is clear that Rom. 1:26-27 can't be fully understood without the surrounding passages. Therefore, we must examine the chapter's other passages, and we should ask ourselves the following questions: